#OOP_D_ITS - 9th - Template

12/04/2023Hadziq Fabroyir - Informatics ITS 1

C++ <Template>


How to implement ↓ in

OOP ?¿several methods with

same function statementsbut take different type of parameters


What are you going to code ?¿

- to express swap function for various data type -


Declare it one by one ?¿

void swapInt (int *a, int *b) ;void swapFloat (float *c, float *d) ;void swapChar (char *p, char *q) ;…

// every methods has a specific name


Make it more general , guys !

One by one declarationFunction Overloading


Function Overloading

void swap (int *a, int *b)

{ int temp; temp = *a; *a = *b; *b = temp; }

void swap (float *c, float *d)

{ float temp; temp = *c; *c = *d; *d = temp; }

void swap (char *p, char *q)

{ char temp; temp = *p; *p = *q; *q = temp; }


Here it is , C++ introduce

<template> !One by one declarationFunction Overloading

Template


Why <templates>C++ promotes code reusability

Inheritance and composition provide a way to re-use object code

Templates provide a way to re-use source code

Example: Queue<T>generic Queue having a type parameter T

T can be replaced with actual types


Why use <templates>

Templates are easier to write. You create only one generic version of your class or function instead of manually creating specializations.

Templates can be easier to understand, since they can provide a straightforward way of abstracting type information.

Templates are type-safe. Because the types that templates act upon are known at compile time, the compiler can perform type checking before errors occur.


<template>

<template>

Function Class


Function Template


What’s it all about

Easily create a large range of related functions or classes

Function template - the blueprint of the related functions

Template function - a specific function made from a function template


Look at this declaration of

Function Template

template <class tipe>

void swap (tipe &a,tipe &b)

{

tipe c;

c = a;

a = b;

b = c;

}


Function Usage Example

Instance of int

void main(void) { int a,b; a = 10; b = 20; swap(a,b); cout << a << “ “ << b << endl;

}

Instance of float

void main(void) {

float a,b;

a = 10.0;

b = 20.0;

swap(a,b);

cout << a << “ “

<< b << endl;

}


<template> effects

It’s reusable ► we can gain the time for coding

It’s possible to swap 2 objects instantiated from a class


Overloading Template Function

#include

<iostream.h>

template <class Tipe>

void swap (Tipe

&a,Tipe &b)

{

Tipe tmp;

tmp = a;

a = b;

b = tmp;

}

void swap(float &a,float

&b)

{

float c;

a = (a < 0.00) ? –a : a;

b = (b < 0.00) ? –b : b;

c = a;

a = b;

b = c;

}


Class Template


Class Templatetemplate <class MyTipe>

class CMyTemplate

{

protected :

MyTipe m_a,m_b;

public :

void Done(void) {

memset (&m_a, 0,

sizeof(MyTipe) );

}

};

/* method is declared

outside the class */

template <class MyTipe>

void

CMyTemplate<MyTipe

>::Init (MyTipe

a,MyTipe b)

{

m_a = a;

m_b = b;

}


Class Template on …

struct

template <class

MyTipe>

struct tMyStruct

{

MyTipe a,b;

};

union

template <class

MyTipe>

union _MyUnion

{

MyTipe a;

int b;

};


Class Template Usage

void main(void)

{

CMyTemplate<short> a;

tMystruct<short> b;

_MyUnion<float> c;

}


Using 2 Type (Example)

template <class MyTipe1,class MyTipe2>

class CMyTemplate {

protected : MyTipe1 m_a MyTipe2

m_b; public :

void Init(MyTipe1 a,MyTipe2 b)

{m_a = a; m_b = b;

} };

void main(void) {

CMyTemplate<short,float> a;

}


For your practice …

Exercise

Declare and Define template for your latest Classes of ...

Shape (ex: public getColor(), protected color)

2D Shape, 3D Shape (ex: public getArea(), protected edgeLength)

Triangle, Circle, Square; Cube, Cylinder, Sphere

Lab Session (Senin, 19.00 – 21.00)

Please provide:the softcopy (send it by email – deadline Sunday 23:59)the hardcopy (bring it when attending the lab session)

12/04/2023Hadziq Fabroyir - Informatics ITS

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#OOP_D_ITS - 9th - Template